As a sub-dialect of Wu dialect, Yixing dialect shares a lot of similarities with other Wu dialects, but also has its own unique sound system and other phonological rules. This paper aims at giving the complete sound system of Yixing dialect and unfolding the phonological rules being responsible for the tone sandhi in Yixing dialect. The paper will be mainly divided into three parts: in the first part, we will focus on analyzing the phonetic features of consonants and vowels in Yixing dialect with the use of Praat， and the diagram of initials and the relative position diagram of monophthongs in Yixing dialect and Mandarin will be derived. In the second part, we will firstly look at the tone patterns in Yixing dialect and then the tone sandhi facts in it. With the help of Praat, we can see clearly how the tones are changed when a word is combined with the other. In the third part, we will focus on the distribution of labiodental fricatives [f] and [v] and also the phonological rules accounting for the distribution will be given.